Multi-rotor wake propagation and flow development modeling: A review

In this work, previous studies focused on wake propagation and flow development of multi-rotor drones are consolidated and discussed. An in depth understanding of wake propagation is critical to accurately predict as it can have adverse effects on vehicle stability and can contaminate in-situ sensor measurements that are placed on the vehicle, such as those which facilitate autonomous maneuvering or atmospheric sampling. Studies that have focused on this issue or similar issues have primarily focused on proximity effects include Computational Fluid Dynamics simulations of wake propagation and multi-rotor flows, and experimental studies using flow visualization and Particle Image Velocimetry to capture multi-rotor wake and flow development. Although some preliminary investigations have been carried out, a comprehensive study has not been conducted that includes research on multi-rotors in vertical flight modes (ascending and descending) which are unique multi-rotor capabilities that are often utilized. An in-depth study of multi-rotor wake development is needed to provide insight into the design and optimization of multi-rotors for various applications, including applications in confined environments or for other applications where the wake propagation significantly impacts mission success.